The Review of Exposure Index in Digital Radiography and Image Quality

디지털 영상에서 화질관리에 관한 노출지수(EI)의 유용성 연구

  • Yang, Sook (Dept. of Radiology, Dongshin university) ;
  • Han, Jae Bok (Dept. of Radiology, Dongshin university) ;
  • Choi, Nam Gil (Dept. of Radiology, Dongshin university) ;
  • Lee, Seong Gil (Deprt. of Radiation Technology, Gwangju Health University)
  • 양숙 (동신대학교 방사선학과) ;
  • 한재복 (동신대학교 방사선학과) ;
  • 최남길 (동신대학교 방사선학과) ;
  • 이성길 (광주보건대학교 방사선과)
  • Received : 2012.12.24
  • Accepted : 2013.01.28
  • Published : 2013.03.30


The aim of this study was to determine the correlation between exposure index (EI) and dose factors related to radiation dose optimization in digital radiography (DR) system. Two phantoms with built-in regional test object for quantitative assessment of images were used to produce image signals that acquired in chest radiography background. EI and entrane surface dose (ESD) increased proportionally with rise of radiation dose (kVp, mAs) in both DR and CR systems. Especially, DR detector was effective to form good contrast and hence, reached easily to improvement of image quality with minimal dose changes. It made operators possible to expect the accuracy of EI values deeply related to absorbed dose of the detector. The evaluation of images was obtained specially employed calculation of noise to signal ratio (NSR) and contrast to noise ratio (CNR). These measurements were performed for how exposure factors affect image quality. NSR was inversely proportional to kVp and mAs and low NSR represented high signal detection efficiency. Consequently, EI values was the measure of the amount of exposure received by the image receptor and it was proportional to exposure factors. Therefore the EI in a recommended range from manufacturer can offer optimal image quality. Also, continuous monitoring of EI values in the digital radiography can reduce the unnecessary patient dose and help the quality control of the system.


Supported by : 동신대학교


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